Pathway control in metallosupramolecular polymerization of a monoalkynylplatinum() terpyridine complex through competitive complex formation

• Published in: Chemical science (Cambridge) 2024-12, Vol.15 (47), p.19729-19738
• Main Authors: Kim, Minhye, Choi, Heekyoung, Kim, Minjoo, Kim, Seonghan, Yun, Seohyeon, Lee, Eunji, Cho, Jaeheung, Jung, Sung Ho, Jung, Jong Hwa
• Format: Article
• Language: English
• Subjects: Addition polymerization; Biomimetic materials; Chemistry; Competitive materials; Complex formation; Complexity; Coordination; Ferrous ions; Iron; Ligands; Platinum; Polymerization; Polymers; Self-assembly; Silver nitrate; Supramolecular polymers
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d4sc06083k

Understanding the pathway complexity of supramolecular polymerization in biomimetic systems has been a challenging issue due to its importance in the development of rationally controlled materials and insight into self-assembly in nature. We herein report a kinetic trapping strategy as a new methodology on how to control the pathway of metallosupramolecular polymerization by employing secondary metal ions and/or ligands which form competitive complex species. For this, we proposed monoalkynylplatinum( ii ) metalloligand (Pt- L 1 ) derived from a bis(amideterpyridine) receptor with one unoccupied terpyridyl terminal as a coordination site for the secondary metal ion (Ag + or Fe 2+ ). The inherent pathway complexity intrinsic to the Pt- L 1 -anchored supramolecular polymerization has been modulated through the incorporation of Ag + or Fe 2+ . During the supramolecular polymerization of Pt- L 1 in the presence of Ag + and Fe 2+ , the added secondary ligand bpy (4,4′-dimethyl-2,2′-bipyridine) or DA18C6 (1,14-diaza-18-crown-6) form complexes as kinetic species, thereby inhibiting spontaneous polymerizations. The supramolecular polymer (SP- I ), with a spherical structure composed of Pt- L 1 in the absence of metal ions as a kinetic product, did not transform into the thermodynamic product, namely supramolecular polymer (SP- III ) with a left-handed fiber structure, due to a high energy barrier. However, the supramolecular polymer (SP- II ) with a left-handed fiber structure, which was formed by Pt- L 1 in the presence of AgNO 3 , converted to SP- III upon the addition of NaCl. Additionally, SP- II transformed into supramolecular polymer (SP- IV ) upon the addition of Fe(BF 4 ) 2 , through an on-pathway process. Both the morphological and emissive characteristics of the resulting supramolecular polymers can be fine-tuned via the Pt Pt or Ag Ag interactions as well as through the changes of the coordination geometry depending on the existing Ag + or Fe 2+ ions. The present results have important implications in expanding the scope of pathway complexity to produce a variety of products via kinetically controlled processes involving secondary metal ions and ligands. The modification of metalloligands based on bis-type amideterpyridine platinum( ii ) complexes not only induces the formation of helical supramolecular polymers but also introduces a kinetic trapping strategy in competitive conditions.